Antenna gain is one of the most important parameters for satellite communications systems since it determines the network coverage and speed. More specifically, more gain means better coverage and higher speed which is critical in the competitive satellite market. The antenna gain over the receive (Rx) band can be critical because, on the satellite side, the receive power at the antenna is very low. This becomes even more critical at scan angles for flat-panel electronically scanned antennas due to the increased attenuation and lower antenna gain at these angles compared to broadside case, making a higher gain value a vital parameter to close the link between the antenna and the satellite. Over the Tx band, the gain is also important since lower gain means more power needs to be supplied to the antenna to achieve the desired signal strength, which means more cost, higher temperature, higher thermal noise, etc.
One type of antenna used in satellite communications is a radial aperture slot array antenna. Recently, there has been a limited number of improvements to the performance of such radial aperture slot array antennas. Dipole loading has been mentioned for use with radial aperture slot array antennas but it shifts the frequency response of the antenna and the improvement is marginal. A slot-dipole concept has also been applied to radial aperture slot array antennas to improve the directivity of the antenna, including to improve the overall return loss performance of the antenna, particularly, antennas operating at broadside.